(n - phenyl - p - toluenesulfonamido)alkyl mercury compounds as silver halide emulsion sensitizers



United States Patent 39/336,735 US. Cl. 96-108 5 Claims Int. Cl. G03c 1/28; G03c 1/34 This invention relates to a process for the production of a light sensitive silver halide photographic emulsion having higher sensitivity.

In the production of a light sensitive silver halide emulsion, various methods for raising the sensitivity have been hitherto known as the so-called chemical sensitizing method, for example, the sulfur sensitizing method by adding a labile sulfur containing compound such as sodium thiosulfate and allylthiourea, followed by heating and ageing, and the reducing method by adding a reducing material such as stannous chloride and hydrazine in small amount, followed by heating and ageing. (Cf. Chimie Photographique 2nd edition, Publication Photocinema, Paul Monter Paris (1957), pp. 297-299.) Some of such labile sulfur containing compounds and reducing materials are considered to be contained in the natural photographic gelatin.

Moreover, some gold salt, for example, aurous thiocyanide has a chemical sensitizing action and methods utilizing such action are well known as the gold sensitizing method. (Cf. ibid, p. 301.)

The object of this invention is to raise the sensitivity of a light sensitive silver halide photographic emulsion.

Now, we have developed a new and effective chemical sensitizing method which does not belong to any of the aforementioned methods.

That is to say, in accordance with the present invention, there is the provision of a method of increasing the sensitivity of a silver halide emulsion by adding 'a compound represented by the following general formula to the emulsion, followed by heating and ageing:

in which R represents alkyl group having 1-3 carbon atoms, phenyl group, tolyl group and benzyl group.

The typical compounds are:

Compound 1: (N-phenyl-p-toluenesulfonamido) ethylmercury Compound 2: (N-phenyl-p-toluenesulfonamido) phenlymercury 3,420,668 Patented Jan. 7, 1969 Compound 3: (N-phenyl-ptoluenesulfonamido) tolylmercury Compound 4: (N-phenyl-p-toluenesulfonamido) benzylmercury Some of inorganic and organic mercury compounds are known as additives which can decrease the fog without losing the sensitivity of a light sensitive material and prevent the increase of the fog during the storage thereof under a high temperature and humidity, being added to a silver halide emulsion in small amount prior to coating on a support (Cf. US. Patents 2,728,6632,728,667, US. Patent 2,732,302 and US. Patent 2,751,299), but the organic mercury compound represented by the foregoing general formula is a new compound that has not been reported as an additive for photographic emulsion in any patent and literature, and furthermore it is found that the addition thereof in the production of a photographic emulsion, above all in the chemical ripening, can bring an effective sensitization and rising of gamma to such an extent that the resulting sensitivity and gamma are not lowered by ageing, while the organic mercury compounds disclosed up to this time are used as fog inhibitors, stabilizers and additives for photographic emulsions after the chemical ripening.

In addition, in the sensitization by the organic mercury compound having the foregoing general formula, the in crease of fog is not only observed, but an effect to suppress the increase of fog can be found even in the ageing, while the sulfur sensitization, reduction sensitization and gold sensitization are inevitably accompanied with the increase of fog.

Some of organic mercury compounds are difficult to add to a photographic emulsion because of their low solubilities in water, but the compound having the foregoing general formula has a water-solubility enough to be used as an additive for photographic emulsions.

Although the chemical sensitizing action of this organic mercury compound is remarkable, in particular, when it is dissolved in water and added to a photographic emulsion in proportion of 0.05-50 mg. to 1 mol of silver halide, the amount to be added may be varied with the kind of the compound and emulsion.

The photographic emulsion whose sensitivity is raised by the process of our invention can be used not only for black-white photography, but also for color photography, and in the latter, it is applied to a support with a coupler for forming color images or the development is carried out by the use of a developing solution containing a conpler for forming color images after it is applied to a support.

As a support to which the photographic emulsion of our invention is applied can be used the conventional support such as glass, cellulose triacetate film base, polyethylene terephthalate film base and baryta paper.

The invention is illustrated in detail by the following examples, but is not limited thereby.

EXAMPLE 1 Aqueous solution of (N-phenyl-p-toluenesulfonylamido)ethylmercury (compound 1) in the amount shown in the following table per 1 mol of silver halide was added to a highly sensitive gelatin-silver iodobrornide emulsion for the neutral process (silver iodide 5.0 mol percent, silver bromide 95.0 mol percent) at the start of the second ripening (chemical ripening), then 10.0 g. of sensitive gelatin containing natural sensitizing sulfur and a gold sensitizer of 1.0 mg. of HAuCl -4H and 80 mg. of KSCN were added thereto in a form of aqueous solution respectively, and the second ripening was carried out at 5 0 C. for 60 minutes with stirring. 30 mg. of 1,1'-diethyl- 2,2-cyanine iodide, 0.45 g. of chrome alum and 0.12 g. of saponin were then added, applied to a film base of cellulose triacetate, dried, subjected to a stepwise exposure of 5400 K. and 1/50 second and developed at 20 C. for minutes by the use of the following developing solution.

Developing solution: G. N-methyl-p-aminophenol sulfate 2.0 Anhydrous sodium sulfite 100.0 Hydroquinone 5.0 Borax 2.0

Water to 1000 ml.

The comparison with a case where (N-phenyl-p-toluenesulfona'mido)ethylmercury is not added but other conditions are the same is shown in the following table, from which it is evident that the sensitizing effect can be raised without the increase of fog.

(N -phenyl-p-toluene-sulfonamide) ethylmereury (compound Relative Gamma Fog 1), per 1 mol of silver halide, mg.) sensitivity EXAMPLE 2 A gelatin-silver chlorobromide photographic emulsion for the fine-grain positive was chilled, nudeled and washed with water, to which 120 mg. of sodium thiosulfate was added per 1 mol of silver halide, and the second ripening (chemical ripening) was carried out at 52 C. for 30 minutes. Thereafter, the mixture was divided into tWo equal portions, to the one of which 10 ml. of 0.001% by weight aqueous solution of (N-phenyl-p-t-oluenesulfonamido)phenylmercury (Compound 2) was added per 1 'mol of silver halide and to the other of which only 10 ml. of distilled water was added for comparison, and the both were further ripened at 52 C. for 30 minutes. The emulsion was applied to a film base of cellulose triacetate and dried to obtain a photographic material having a coating of 12 micron in thickness. Then, it was subjected to a stepwise exposure of 2660 K. light source and 1/ 20 second and developed at 20 C. for 4 minutes by the following developing solution, followed by fixing, washing with water, drying and sensitometry.

Water to 1000 ml.

The results are shown in the following table, from which it is evident that the sensitizing effect can be given without increase of fog.

Relative Gamma Fog sensitivity No 100 2.52 0.05 (N-phenyl-prtoluenesulfonylamido)- phenylmercury (compound 2) added 0.04

4 EXAMPLE 3 A gelatin-silver iodobrornide emulsion (silver iodide 2.2 mol percent, silver bromide 97.8 mol percent for the ammonia process was washed with water, mixed with the following compounds per 1 mol of silver halide and the second ripening (chemical ripening) was carried out at 50 C. for 40 minutes:

Example 3 Triethylthiourea 0.01% by weight metanol solution, 1.2

HAllClr 41120 by weight aqueous solution, 5.0

NHASCN 0.1 l l cfi i eous solution, 4.0 ml.

G. 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene 0.3 Chrome alum 0.2 Saponin 0.2

Thereafter, the emulsion was applied to a cellulose triacetate film and dried to give a light sensitive material having a coating of 12 micron in thickness.

These two films were exposed to light stepwise at 5400 K. and developed by the following developing solution at 20 C. for 4 minutes.

Developing solution: G. N-methyl-p-aminophenol sulfate 4.0 Anhydrous sodium sulfite 60.0 Hydroquinone 10.0 Sodium carbonate (mono-hydrate) 53.0 Potassium bromide 3.0

Water to 1000 ml.

The comparison with a case where (N-phenyl-p-toluenesulfonamido)tolylrnercury is not added but other conditions are the same is shown in the following table, from which it is evident that the sensitizing effect can be raised without the increase of fog.

Relative Gamma Fog sensitivity No 1.72 0. 03 (N-phenyl-p-toluenesulfonamido)- tolyl-mercury (compound 3) 126 1. 01 0.03

EXAMPLE 4 Aqueous solution of (N-phenyl-p-toluenesulfonamido) benzylmercury (compound 4) in the amount shown in the following table per 1 mol of silver halide was added to a highly sensitive gelatin-silver iodobrornide emulsion (silver iodide 5.0 mol percent, silver bromide 95.0 mol percent) for the neutral process at the start of the second ripening (chemical ripening), then 8.0 g. of active gelatin containing natural sensitizing sulfur and a gold sensitizer of 7.5 mg. of HAllCl '4H O and mg. of KSCN were added thereto in a fonrn. of aqueous solution respectively, and the second ripening was carried out at 50 C. for 90 minutes with stirring. 30 mg. of 1,1-diethyl- 2,2-cyanine iodide, 0.45 g. of chrome alum and 0.12 g. of saponin were then added, applied to a film base of cellulose triacetate, dried, subjected to a stepwise exposure of 5400 K. and 1/20 second and developed at 27 C. for 3 minutes 30 seconds by the use of the following developing solution.

Water to 1000 ml.

The comparison with a case where (N-phenyl-p-toluenesulfonamido)benzylmercury is not added but other conditions are the same is shown in the following table, from which it is evident that the sensitizing effect can be raised without the increase of fog.

(N -phenyl-p-toluene-sulfonamido)- benzyl-mercury (compound 4) Sensitivity Gamma Fog I per 1 mol of silver halide (mg) What is claimed is:

1. A light sensitive silver halide photographic emulsion, into which has been incorproated, during the production of the emulsion, a compound represented by the general formula in which R represents a member selected from the class consisting of alkyl group having l-3 carbon atoms, phenyl group, tolyl group and benzyl group.

2. The photographic emulsion according to claim 1 wherein said compound is shown by the formula:

(N-phenyl-p-toluenesulfonamido) ethylm-ercury.

3. The photographic emulsion according to claim 1 wherein said compound is shown by the formula:

5 Q-Hg-N-SOa-Q-CH:

(N-phenyl-p-toluenesulfonamido) phenylmercury.

4. The photographic emulsion according to claim 1 wherein said compound is shown by the formula:

Hg-N-SO2CH3 (N-phenyl-p-toluenesulfonamido)benzylmercury.

5. The photographic emulsion according to claim 1 wherein said compound is shown by the formula:

(N-phenyl-p-toluenesulfonamido)benzylmercury.

References Cited UNITED STATES PATENTS 3,137,577 6/1964 Miura et al 96l08 3,179,520 5/1965 Miura et al 96-107 NORMAN G. TORCHIN, Primary Examiner.

J. R. EVERETT, Assistant Examiner.

US. Cl. X.R. 

1. A LIGHT SENSITIVE SILVER HALIDE PHOTOGRAPHIC EMULSION, INTO WHICH HAS BEEN INCORPROATED, DURING THE PRODUCTION OF THE EMULSION, A COMPOUND REPRESENTED BY THE GENERAL FORMULA: 